1. Field of the Invention
The present invention relates to a temperature control device that is suitable for the temperature control of substrates, such as semiconductor wafers, and in particular, to the improvement of a temperature control device using a semiconductor heat exchange device utilizing the Peltier effect and a method for manufacturing the same.
2. Description of the Related Art
Conventionally, temperature control devices for controlling the temperature of substrates, such as semiconductor wafers, are known that are provided with a semiconductor thermoelectric conversion module (referred to as xe2x80x9cthermoelectric modulexe2x80x9d in the following) utilizing the Peltier effect as a means for heating or cooling. In such temperature control devices, thermoelectric modules are sandwiched between a plate for mounting the object to be temperature-controlled and a plate for heat exchange. Usually, the thermoelectric modules are two-dimensional arrangements of a multitude of rectangular solid-shaped p-type semiconductor elements and n-type semiconductor elements, which are coupled to xcfx80-shapes by electrodes and electrically connected in series, sandwiched between two rectangular ceramic plates. When current flows through the thermoelectric modules, due to the Peltier effect, the surface (heat exchange surface) of the ceramic plate on one side absorbs heat, whereas the surface (heat exchange surface) of the ceramic plate on the other side releases heat.
When for example cooling the object to be temperature-controlled with this temperature control device, the thermoelectric modules are driven so as to absorb heat on the side of the mounting plate and to release heat on the heat exchange plate. Then, the heat exchange plate takes away the heat from the thermoelectric modules, for example with cooling water flowing inside it.
This type of conventional temperature control device is manufactured as follows. First, depending on the size of the temperature control device, a number of thermoelectric modules is prepared. Since one thermoelectric module has a size of not more than several cm by several cm, a multitude of thermoelectric modules are necessary to produce a temperature control device for a wafer of, for example, 30 cm diameter, because the diameter of the temperature control device exceeds those 30 cm. Then, thermally conducting grease is applied to both heat exchange surfaces of the thermoelectric modules. Then, the thermoelectric modules are sandwiched between the mounting plate and the heat exchange plate, and the thermoelectric modules are pressed against the two plates by applying pressure to the outside surfaces of the two plates. Then, while pressing the thermoelectric modules against the two plates, the two plates are fastened to one another with a plurality of bolts, fixing the positions of the thermoelectric modules between the two plates. Fastening the bolts, the plates and the thermoelectric modules are pressed against each other with a large force, so that the plates and the thermoelectric modules are in close contact and a sufficiently large contact area between the plates and the thermoelectric modules can be ensured even when there are slight irregularities in the surface of the plates.
However, in this conventional method for manufacturing a temperature control device, there is the problem that the steps for fastening the bolts make the method labor-intensive. Moreover, when the bolts are tightened too much, the plates may be inadvertently deformed. Furthermore, when there are variations in the tightening degree of the individual bolts, then there is the danger of deficiencies such as positional misalignments of the thermoelectric modules, or the projecting of the thermoelectric modules from between the plates. Moreover, when the positions where the plates can be attached to the bolts are restricted due to the strength of the plates and the arrangement of the water ducts in the heat exchange plate, then this also puts limitations to the positions where the thermoelectric modules can be attached, and as a result, there are the problems that irregularities occur in the temperature distribution in the surface of the mounting plate, and that the capability to adjust all portions of the object to be temperature-controlled to the same temperature, that is, the temperature uniformity worsens. Moreover, in the conventional temperature control device, ceramic plates are inserted between the thermoelectric modules and the plates for electric insulation between those parts, so that these ceramic plates act as heat resistances, and in particular due to the heat resistance of the ceramic plate on the side of the mounting plate, it is not possible to achieve a sufficient thermal response with respect to the object to be temperature-controlled. Therefore, it is not possible to adjust the temperature of the object to be temperature-controlled quickly to the desired temperature.
It is therefore an object of the present invention to provide a temperature control device with excellent temperature uniformity and thermal response, which can be manufactured easily, and a manufacturing method for the same.
A temperature control device in accordance with the present invention includes a mounting plate for mounting an object to be temperature-controlled; a heat exchange plate for the exchange of heat; a heat exchange device having a multitude of thermoelectric conversion elements that are sandwiched between said two plates and arranged in a two-dimensional arrangement, and a multitude of electrodes that are electrically connected to these thermoelectric conversion elements and that have heat exchange surfaces on both sides. The multitude of thermoelectric conversion elements of the heat exchange device is distributed across substantially an entire temperature control region that covers the region corresponding to the object to be temperature-controlled that is mounted on the mounting plate.
With this invention, the thermoelectric conversion elements can be distributed densely across the entire temperature control region that covers the region corresponding to the object to be temperature-controlled, so that temperature uniformity can be attained reliably.
In a preferable embodiment, all of the thermoelectric conversion elements included in the heat exchange device are connected electrically in series. Moreover, the electrodes are made of metal foil, for instance, copper foil or stainless steel foil.
In a preferable embodiment, the heat exchange surfaces on at least one side of the heat exchange device are fixed to the mounting plate or the heat exchange plate with an adhesive. The adhesive is electrically insulating, and the heat exchange surfaces on at least one side of the heat exchange device are directly adhered to the mounting plate or the heat exchange plate with this adhesive. The total thickness of the adhesive and the electrodes on the side that is fixed with the adhesive is approximately 25 to 100 xcexcm.
In a preferable embodiment, the surface of the mounting plate or the heat exchange plate is coated with an insulating material, and the heat exchange surfaces on at least one side of the heat exchange device are adhered to this coated surface.
In a preferable embodiment, the heat exchange surfaces on at least one side of the heat exchange device are attached in a slidable manner to the mounting plate or the heat exchange plate, and the heat exchange surfaces on the other side of the heat exchange device are fixed to the mounting plate or the heat exchange plate. The heat exchange surfaces on the other side are directly adhered to the mounting plate or the heat exchange plate with an adhesive that is electrically insulating. More preferably, the heat exchange surfaces on one side of the heat exchange device are slidable with respect to the heat exchange plate, and the heat exchange surfaces on the other side are adhered to the mounting plate with the adhesive.
In a preferable embodiment, the mounting plate is a flexible sheet.
In a preferable embodiment, a plurality of the heat exchange devices are stacked one upon the other with the heat exchange surfaces arranged in series. In this case, the plurality of the heat exchange devices are adhered to one another with an electrically insulating adhesive.
A preferable embodiment further includes a reinforcement material provided between the mounting plate and the heat exchange plate. This reinforcement material can be a lattice-shaped member, electrically insulating the thermoelectric conversion elements included in the heat conversion device.
A preferable embodiment further includes a jig for arranging the thermoelectric conversion elements of the heat exchange device between the mounting plate and the heat exchange plate.
A preferable embodiment further includes a duct for cooling water inside the heat exchange plate.
In a preferable embodiment, the mounting plate is a heat plate provided with one or more heat pipes.
A method for manufacturing a temperature control device in accordance with a first aspect of the present invention includes a first step of adhering a metal foil to a surface of an adhesive sheet; a second step following the first step, in which a pattern is etched into the metal foil on the surface of the adhesive sheet, so as to form electrodes having a predetermined wiring pattern; a third step following the second step, in which the adhesive sheet is adhered to one surface of the mounting plate or the heat exchange plate; and a fourth step following the second step, in which the thermoelectric conversion elements are connected to predetermined positions on the metal foil electrodes.
A method for manufacturing a temperature control device in accordance with a second aspect of the present invention includes a first step of adhering a metal foil to a surface of an adhesive sheet; a second step of adhering the adhesive sheet to one surface of the mounting plate or the heat exchange plate; a third step following the first step and the second step, in which a pattern is etched into the metal foil on the adhesive sheet, so as to form electrodes having a predetermined pattern on the adhesive sheet; a fourth step following the third step, in which the thermoelectric conversion elements are connected to predetermined positions on the metal foil electrodes.
In a preferable embodiment, the adhesion with the adhesive sheet is carried out by heating the adhesive sheet and fusing it.
In a preferable embodiment, when electrically connecting the thermoelectric conversion elements, a jig for attaching the thermoelectric conversion elements is used that has through holes for setting the thermoelectric conversion elements, wherein the through holes are formed in accordance with the pattern in which the thermoelectric conversion elements are arranged.